ANODIC-DISSOLUTION OF ANTIMONY IN PHOSPHATE SOLUTIONS

The anodic dissolution of antimony in alkaline phosphate solutions has been investigated by using a galvanostatic technique. The rate of anodic dissolution was found to depend on pH and showed a Tafel slope of 195 mV/decade. The reaction order with respect to OH- was found to approximately equal to one. The dissolution rate of antimony at constant pH value is increased with solution stirring and dissolution temperature. The activation energy ΔH* for the anodic dissolution process was found to be 20.3 kcal·mol-1. °K-1. The anion nature affected the anodic dissolution at pH 7.0, while at pH 12 the same anions have no effect. The dissolution rate of antimony is increased with increasing the phosphate ion concentration up to 1.0 N; higher concentration than this value decreased the dissolution.